Semantic interoperability

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Semantic Interoperability is the ability of two or more computer systems to exchange information and have the meaning of that information accurately and automatically interpreted by the receiving system.

Interoperability is sometimes considered as an all-or-nothing attribute of computer systems, but for complex information, different levels of interoperability can be envisioned; when multiple pieces of information are being transferred, correct interpretation of some fraction of that information may be considered as constituting some level of semantic interoperability. Perfect semantic interoperability would require the correct interpretation of all transferred information.

The goal of efforts at empowering computer systems with semantic interoperability rests on the desirability of computer systems being able to find information and to use it for purposes that the original creator of the information did not anticipate. This goal of flexible information reuse requires some degree of understanding of the information, which in turn requires that the information be encoded in some standard fashion that is interpreted identically by all systems using that information.

To achieve the level of understanding usually implied by the term semantic interoperability requires the use of a knowledge representation language that is sufficiently expressive to describe all the nuances of meaning that are significant to the task at hand. This level of expressiveness will require an ontology with at least the full power of first-order logic for many tasks, though for some restricted tasks a description logic (such as the one used in the OWL semantic web ontology language), having an expressiveness somewhat less than first order, will be adequate. Human languages are highly expressive, but are considered too ambiguous to allow the accurate interpretation desired, given the current level of human language technology. To achieve perfect semantic interoperability, all communicating systems must use term (or symbol) definitions that are identical or can be accurately interconverted. Thus a common ontology is the ideal situation for semantic interoperability. Where that is impossible, lesser degrees of semantic interoperability may be achieved by techniques that automatically map the definitions used by one system to those of another.

Semantic interoperability may be distinguished from other forms of interoperability by considering whether the information transferred has, in its communicated form, all of the meaning required for the receiving system to interpret it correctly, even when the algorithms used by the receiving system are unknown to the sending system. To make this concrete, consider transmission of a number between two systems. If that number is intended to be the sum of money owed by one company to another, it may be correctly interpreted if sent in response to a specific request, and received at the time and in the form expected. But this correct interpretation does not depend only on the number itself, which could represent almost any of millions of types of quantitative measure, rather it depends strictly on the circumstances of transmission. That is, the interpretation depends on both systems expecting that the algorithms in the other system use the number in exactly the same sense, and it depends further on the entire envelope of transmissions that preceded the actual transmission of the bare number. By contrast, if the transmitting system does not know how the information will be used by other systems, it is necessary to have a shared agreement on how information with some specific meaning (out of many possible meanings) will appear in a communication. For a particular task, one solution is to standardize a form, such as a request for payment; that request would have to encode, in standardized fashion, all of the information needed to evaluate it, such as: the agent owing the money, the agent owed the money, the nature of the action giving rise to the debt, the agents, goods, services, and other participants in that action; the time of the action; the amount owed and currency in which the debt is reckoned; the time allowed for payment; the form of payment demanded; and other information. When two or more systems have agreed on how to interpret the information in such a request, they can achieve semantic interoperability for that specific type of transaction. But for semantic interoperability generally, it is necessary to provide standardized ways to describe the meanings of many more things than just commercial transactions, and the number of concepts whose representation needs to be agreed upon are at a minimum several thousands.

How to achieve semantic interoperability for more than a few restricted scenarios is currently a matter of research and discussion. Some form of agreed common ontology, at least one that is sufficiently high-level to provide the defining concepts for more specialized ontologies, is believed by some to be essential. But there is as yet no single ontology accepted and used by more than a small number of leading-edge research groups. Whether use of a single high-level ontology can be avoided by sophisticated mapping techniques among independently developed ontologies is under investigation.

[edit] See also

For Interoperability generally see the Wiki article: Interoperability Discussion of using an upper ontology:: Upper ontology (computer science)

A general discussion including semantic interoperability with an interoperability spectrum can be found at

• Levels of Conceptual Interoperability

[edit] External links

Other definitions of Semantic Interoperability can be found in the ONTACWG Glossary